A new NASA study reveals that the Antarctica Larsen B Ice Shelf is weakening fast and will likely disintegrate totally before the end of the decade. Part of the ice in that area collapsed partially in 2002, and now is quickly flowing, increasingly fragmented and developing huge cracks. Two of its glaciers are rapidly thinning and flowing.
The 625-square mile remains of Larsen B on the coast of the Antarctic Peninsula is about 500 meters when thickest, which, according to USA Today, is roughly similar to the size of 27 islands in Manhattan. This ice exists for at least 10,000 years and will be gone before long. It will likely shatter into icebergs before the end of this decade. It is already floating ice, thus, the ice shelf collapse will not contribute directly to the rise of the sea level worldwide.
The three major tributary glaciers of Larsen B are Leppard, Starbuck and Flask with Starbuck and Flask named after the characters in Moby Dick. Their flow speed and thickness altered a bit after 2002. While the researchers assume they are stable, a new study revealed that Leppard and Flask thinned by 20 to 22 meters. Flask had accelerated 36 percent by 2012 to a flow speed of 700 meters a year, which is like a car running from 55 – 75 mph.
In the Jet Propulsion Laboratory of NASA in Pasadena, California, a team led by Ala Khazendar, found that the ice remnant is disintegrating as the signs warn. Khazendar said that though it is scientifically fascinating to behold the ice shelf breaking up, it is bad news for the planet.
Ice shelves keep the glaciers from flowing towards the ocean from Antarctica; otherwise, the glacial ice enters the ocean fast and increases the rise of the global sea. This NASA study is the first to look at the Larsen B remnant closely, as well as the glaciers that flow into it. It has been online in the Earth and Planetary Science Letters.
In NASA’s revelation that the Antarctica ice will disintegrate before the end of the decade, the study team utilizes bedrock depth and surface elevation information from instrumented aircraft, which is with the agency’s Operation IceBridge, an airborne survey campaign, that provides annual documentation of the glaciers in Antarctica, as well as its ice sheets and ice shelves. The information about the speed of the flow was retrieved from the spaceborne synthetic aperture radars which are in operation since 1997.
Meanwhile, the estimate on the remaining life of the ice remnant, as Khazendar noted, is based on the imminent cracking all the way across of the widening big hole near the grounding line of the ice shelf. The remnant that is freely flowing will eventually become hundreds of icebergs that will glide away. Without any hindrance, the glaciers will then expedite their move to the sea.
The surprising thing about Larsen B, said Khazendar, is that its changes are happening fast and have been persistent. The glaciers at the back of the part which collapsed in 2002, accelerated as much as eight times, just like a car that runs from 55 – 440 mph. Glacier Starbuck changes a bit, as its channel is narrower than the other glaciers, and which is anchored strongly to the bedrock.
NASA’s study which reveals that the Larsen B Antartica Ice will likely disintegrate completely before the end of the decade gives insights about how the shelves of the ice in the south, reacts to warmer climate, said Eric Rignot, a JPL glaciologist and coauthor of the paper. NASA’s research team on the Larsen B Ice has scientists from JPL, Irvine, University of California and Norway’s University Centre in Svalbard.
By Judith Aparri
NASA: NASA Study Shows Antarctica’s Larsen B Ice Shelf Nearing Its Final Act
USA Today: Huge ice shelf in Antarctica to collapse by 2020
io9: Antarctica’s Larsen B Ice Shelf Will Likely Disintegrate By Decade’s End
Photo courtesy of Liam Quinn’s Flickr Page – Creative Commons License